Deded Yudha Pranathadr. Bambang Gunawan, SpOT

Blood Calcium, Phosphorus, and Magnesium

Basic Orthopaedic Tutorial

Regulator: PTH ; 1,25 (OH)2 vit D ; Calcitonin

The metabolically active tissues :1. Bones2. Kidneys3. Intestine

CALCIUM

Normal level: 9.0 – 10.4 mg / 100 mL

99%

1%

Absorption Active transport – duodenum▪ Require ATP & regulated by vit D

Passive diffusion – jejunum

Reabsorption 98% ca reabsobed in kidney

Calcium Diet

Dietary requirement Children : 600 mg/ day Adolescent & young adult : 1300 mg / day Adult : 750 mg / day Pregnant women : 1500 mg / day Lactating women : 2000 mg /day Post menopausal women : 1500 mg / day Patients w/ a long bone fracture: 1500 mg /

day

Functions of Calcium

Controls internal regulation of function of all cells

Regulates cell membrane permeability, nerve excitability, muscle contraction, and gland secretion

Regulates synthetic and secretory functions of PTH and thyroid C cells (for calcitonin)

Control adhesiveness between cells Controls the hardness and rigidity of

bones and teeth through hydroxyapatite

Calcium homeostasis

Normal Calcium and Phosphate Metabolism

Ca Related Metabolic Bone DiseasesDisease Etiology

Hypercalcemia

HyperPTH PTH overproduction -adenoma

Familial syndromes PTH overproduction - Multiple endocrine neoplasia type I and II

Hypocalcemia

HypoPTH PTH underproduction – idiopathic, iatrogenic

Pseudohypoparathyroidism / Albright syndrome

PTH receptor abnormality

Renal Osteodystrophy CRF – Pi excretion ↓

Rickets (Osteomalacia) Nutritional, vit D dependent, vit D resistant

Renal osteodystrophy

Phosphate (Pi)Normal level : 2.8 – 4.0 mg/dL

85% boneReabsorption kidney (renal tubular) 70 –

90%Stimulated by 1,25 (OH)2 DInhibited by PTHDaily requirements: 1000 – 1500 mg/ day

Together with Ca – normal bone metabolism

Phosphate homeostasis

Small role in bone homeostasis Required for parathyroid hormone secretion. Efficient peripheral action of PTH

◦ cofactor

Magnesium

Thank you